MYOLOGY 87 



quadratus plantae adductor digiti quarti 



lumbricales adductor digiti secundi 



flexor hallucis interossei 

 abductor hallucis 



M. extensor digitorum brevis (fig. 18) is the only 

 muscle upon the dorsum of the pes. Origin of its few 

 fibers is from the cranial part of the calcaneal annular 

 ligament. Two thread-like tendons develop which extend 

 to insertions upon the extreme lateral sides of digits two 

 and three. 



M. flexor digitorum brevis (fig. 18) constitutes the 

 main continuation, over the heel, of the plantaris. It de- 

 velops muscle fibers upon both the ectal and ental sur- 

 faces of the deeper division of the plantar ligament of the 

 plantaris, which are inserted chiefly upon the lateral three 

 or four tendinous branches which pass, respectively, to the 

 four lateral digits. The lateral portion of the main tendon 

 consists of a separate tendinous sUp, arising from the 

 membranous investment of the calcaneum. 



M. quadratus plantae (accessorius) (fig. 18). This 

 muscle does not have two separate heads in the present 

 genus, although the origin is continuous both from the 

 ventral head of the os calcis, and fleshy from the lateral 

 and medial parts of this bone. Insertion is upon the 

 peroneal process of metatarsus five. 



Mm. lumbricales (fig. 18) are four in number. They 

 develop from the tendon of the flexor fibularis, which 

 tendon is more intimately concerned with the latter muscle 

 than the digitorum longus, as is often the case. Their 

 insertions are upon the tendinous branches extending to 

 the four lateral digits. 



M. flexor hallucis (fig. 18) seems to occur in two divi- 

 sions. The first has origin from the entocuneiform and is 

 inserted onto the external tarso-phalangeal sesamoid. The 

 more medial division, which may really constitute one of 



